A look at the criteria used to rate state legislatures' likely action if Roe v. Wade were overturned. (Some states have characteristics that fall into more than one category; the ranking reflects consideration of multiple factors.)

1. States considered likely to enact significant additional restrictions on abortion:

• Some have in place "trigger" laws -- bans on abortion that would take effect if Roe were reversed.

• Some are debating bans on abortion or "trigger" laws this year, or are gathering signatures for a ballot initiative to ban abortion.

• All have passed eight or more of 11 current restrictions on abortion tracked by the Alan Guttmacher Institute.

2. States in the middle:

• None has an abortion ban that would be triggered by Roe's reversal.

• None has enacted legislation to protect access to abortion if Roe were reversed.

• All have passed four to nine of the 11 current restrictions on abortion tracked by the Guttmacher Institute.

3. States considered most likely to protect access to abortion:

• Some have enacted laws that would ensure abortion rights if Roe were overturned.

The U.S. Supreme Court ruled in Roe v. Wade in 1973 that a Texas law criminalizing most abortions violated a woman's constitutional right of privacy, which the court said was implicit in the due-process clause of the 14th Amendment.

"Jane Roe" was an alias used to shield the identity of Norma McCorvey, who sued Dallas County District Attorney Henry Wade.

In the 7-2 decision, the court sought to balance a woman's right to privacy with a state's interest in regulating abortion. Only a "compelling state interest" would justify restrictions, it concluded. Legal challenges have limited the reach of Roe but not overturned it.

COLUMBUS, Ohio  Two hours after South Dakota Gov. Mike Rounds signed an abortion ban last month, NARAL Pro-Choice America blasted an e-mail to its supporters: "Is your state next?"

The South Dakota legislation and the abortion rights group's warning are early skirmishes in a battle over what states would do if the landmark Roe v. Wade decision were overturned — though both sides concede that may never happen.

If it does, a fight that for three decades has focused on nine members of the Supreme Court would be waged instead among more than 7,000 legislators in 50 state capitals.

"Now is the time to get moving on this in Ohio," says Tom Brinkman, a state legislator who has introduced a bill to ban almost all abortions. Meanwhile, Kellie Copeland of NARAL Pro-Choice Ohio is braced. "Our supporters feel the fight is coming back to the states," she says.

What would states do?

Ultimately, that would depend on factors ranging from who was governor to where public opinion stood. Even so, there are clues from what state legislatures have chosen to do already and what they're considering doing next.

For instance, four states have passed "trigger" bans on abortion that would go into effect immediately if Roe were reversed. Six other states have passed laws that would automatically protect access to abortion. Three states have enacted all 11 of the current restrictions on abortion tracked by the non-profit Alan Guttmacher Institute, from requiring waiting periods to limiting abortion coverage in insurance plans. One state, Vermont, hasn't passed any restriction.

USA TODAY used the Guttmacher data and other factors to calculate how states would be likely to respond if Roe were reversed. The 1973 decision recognized access to abortion as part of a constitutional right to privacy and limited states' ability to restrict it.

The conclusions:

•Twenty-two state legislatures are likely to impose significant new restrictions on abortion. They include nearly every state in the South and a swath of big states across the industrial Rust Belt, from Pennsylvania to Ohio and Michigan. These states have enacted most of the abortion restrictions now allowed.

Nine states are considering bans similar to the one passed in South Dakota — it's scheduled to go into effect July 1 — and four states are debating restrictions that would be triggered if the Supreme Court overturned Roe.

•Sixteen state legislatures are likely to continue current access to abortion. They include every state on the West Coast and almost every state in the Northeast. A half-dozen already have passed laws that specifically protect abortion rights. Most of the states in this group have enacted fewer than half of the abortion restrictions now available to states.

•Twelve states fall into a middle ground between those two categories. About half are in the Midwest, the rest scattered from Arizona to Rhode Island.

The result, according to this analysis, would be less a patchwork of laws than broad regional divisions that generally reinforce the nation's political split. All but three of the states likely to significantly restrict abortions voted for President Bush in 2004. All but four of the states likely to maintain access to abortion voted for Democrat John Kerry.

The 22 states likely to enact new restrictions include 50% of the U.S. population and accounted for 37% of the abortions performed in 2000, the latest year for which complete data were available.

The 16 states likely to protect access to abortion include 35% of the U.S. population and accounted for 48% of the abortions performed.

Other factors to weigh

There are some factors that this analysis doesn't take into account.

Among the states ranked as likely to enact new restrictions, Michigan and Wisconsin now have governors who support abortion rights and presumably would veto a ban if they were still in office. Courts in Florida and Tennessee have ruled that their state constitutions protect abortion rights, limiting the impact of Roe's reversal.

(That's not necessarily an insurmountable hurdle, though: Florida voters amended the state constitution in 2004 to allow a law requiring minors seeking abortions to notify their parents, and Tennessee activists are pursuing a constitutional amendment to limit abortion rights there.)

The states ranked as likely to continue current access to abortion could be pre-empted if Congress passed laws that restricted or criminalized abortion nationwide.

And first things first: Reversing Roe may be a more distant prospect than activists in both camps think. It would require a change of heart or retirement by at least one of the five current Supreme Court justices who have endorsed it.

What's more, while the confirmation of two new justices has heartened abortion foes, neither Chief Justice John Roberts nor Justice Samuel Alito has said clearly where he stands on Roe.

In Ohio, Brinkman, a three-term legislator and father of six, acknowledges that he may be rushing things with the bill he has submitted to ban all abortions in the state except those necessary to save the life of the woman.

But the 48-year-old Republican, who owns a small printing firm in suburban Cincinnati, predicts it's just a matter of time. "It will happen," he declares in an interview just off the floor of the ornate House chamber.

Copeland says Brinkman and other abortion opponents "feel emboldened" by the latest appointments to the U.S. Supreme Court. "We're going to be fighting more and more bills," she says.

Going beyond current law

Ohio already has done nearly all it can to restrict abortions. The state requires women seeking abortions to be told about alternatives and then to wait at least 24 hours. Hospitals and doctors can refuse to perform them. Minors must get a parent's consent. A controversial late-term procedure that opponents call "partial-birth abortion" is barred.

Brinkman's bill would go much further. It would make performing an abortion or transporting a woman across state lines to have an abortion a felony.

Another proposal, sponsored by Rep. Michelle Schneider, also a Republican, would ban abortions at state-funded hospitals and by public employees except those needed to save the life of the mother or mandated by the federal Medicaid program. It would declare that "the public policy of the state of Ohio (is) to prefer childbirth over abortion to the extent that is constitutionally permissible."

"It's not the golden ring that a lot of the anti-abortion people want," concedes Schneider, who owns a nursing home and home health care business in the Cincinnati suburb of Madeira. She supports Brinkman's ban but says she worries that it "could take years and years" to test in the courts.

"My bill would take the state of Ohio out of the abortion business" right now, she says.

There's no guarantee that the Legislature will vote on either measure this year. Ohio Republicans already are navigating difficult waters. Gov. Bob Taft is retiring after being convicted of ethics charges. U.S. Sen. Mike DeWine faces a tough re-election fight. U.S. Rep. Bob Ney is enmeshed in the investigation into disgraced lobbyist Jack Abramoff, although Ney denies wrongdoing.

Some of his fellow Republican officials worry that a debate over abortion could provoke a backlash among moderate voters, Brinkman acknowledges.

John Green, a political scientist at the University of Akron, agrees. "A lot of Republicans think there's enough controversy on the table anyway, without having to add the abortion issue," he says.

Still, Brinkman boasts that a hearing finally has been scheduled on his bill for early next month, and he notes that the Assembly plans a lame-duck session after the November elections. If a Democrat is elected governor, the Republican-controlled Legislature might rush to enact legislation that Taft can sign before leaving office.

"We could have a substantial lame-duck session — more substantial if a Democrat governor got elected," Brinkman says.

Either bill would have some prospect of passing.

House Democratic leader Joyce Beatty, 56, a small-business owner from Columbus who has been a chief statehouse defender of abortion rights, says flatly: "If we voted on this tomorrow in this House, I would lose." She estimates that one-third of her fellow Democrats join nearly all Republican legislators in opposing abortion.

Promises, but no guarantees

In fact, 63 of the 99 members of the Ohio House are committed, if Roe is overturned, to support a state ban on abortions except those needed to save the life of the woman. (Seven members add exceptions in cases of rape and incest.) Their pledges are posted on the website of Ohio Right to Life, which conducted a candidates' survey during the 2004 campaign.

Even that is no guarantee, says Denise Mackura, director of governmental relations for the anti-abortion group. "What candidates say in their surveys sometimes doesn't come to pass," she says. "People who said they were pro-life as a matter of expediency — I'd like to think they're not many, but that would be naïve."

Both sides are now mustering volunteers for post-Roe battles. NARAL Pro-Choice Ohio works out of a cramped bay-window office in a historic neighborhood a mile from the state Capitol in the center of the city. Ohio Right to Life fills a warren of offices on the second floor of a nondescript office building at the outskirts of town.

Mackura, 54, a lawyer by training who has been working in the anti-abortion movement since her college days, says her group already has supporters lined up in every district, ready to hold state legislators to their campaign promises.

Copeland, 36, a former organizer for the AFL-CIO, hopes the intense debate sure to be sparked if a state ban was a legal possibility, not a hypothetical question, would persuade some legislators to change their minds.

She notes that the Roe decision consistently commands majority support in public opinion surveys. The USA TODAY/CNN/Gallup Poll in January found that Americans backed it by 66%-25%. In the survey, 53% said they considered themselves "pro-choice" and 42% said they were "pro-life," a breakdown that has stayed about the same for a decade.

In a USA TODAY poll last month, six of 10 Americans opposed statewide bans on abortion; 36% supported them.

'A little bit of encouragement'

There wasn't much difference on that issue by gender or age, but there was by political party. A ban that would permit abortions only to save the life of the mother was supported by 54% of Republicans but opposed by 66% of Democrats and 70% of independents.

That's one reason some anti-abortion leaders are leery of moving too quickly to push broad restrictions.

"We still need to change the culture," Mackura says, and she cautions against assuming that Roe is history. Ohio Right to Life supports Brinkman's goal but hasn't endorsed his bill. "Sometimes when you get a little bit of encouragement you get very excited and you think, 'This is the time to do it,' " only to be disappointed, she says.

In contrast, groups on the other side of the issue are using the prospect of battles in state capitals to rouse those who support abortion rights but haven't seen the issue as a priority. Nancy Keenan, president of NARAL Pro-Choice America, says half of the first 900 contributions from the South Dakota appeal came from people who hadn't contributed to the group before.

Determining abortion restrictions state-by-state only makes sense to Dorothy Timbs, legislative counsel for the department of state legislation at National Right to Life.

"Obviously the issue would return back to the states to decide for themselves," she says. "We believe an issue as sensitive as abortion, that affects so many women and their children, should be up to their legislators who are accountable to the people."

Nancy Northrup, president of the Center for Reproductive Rights, protests that overturning Roe would make access to a fundamental right dependent on geography. She predicts it will inflame what is already one of the most divisive issues in American politics. "It is going to make abortion the center of every local race for office, every state legislative race, of every state judicial race, of every state executive race, not to mention a battle for federal elections," she says. "It will be a never-ending battle."